Introduction

The Kast Double Spectrograph is used at the cassegrain focus of the
Shane 3-m Telescope. It is two separate spectrographs - one optimized
for the red, the other for blue - housed in a single structure and
having some components in common. Each side offers a selection of
dispersive elements for various resolutions and dispersions, and both
are also capable of direct imaging over a limited field. Dichroic
beamsplitters and separate CCD detectors allow simultaneous
observations in red and blue. A polarimeter is also available for
spectropolarimetry observations.

News:
Oct 4, 2016: New dichroic beamsplitters are now available. One has a
transition wavelength of 5700 A, and the other is a new 4600 A
dichroic intended as a replacement for the existing 4600 A dichroic (and will
be the default D4600 starting 2017A, programs requiring the old D4600 should
note that as a special instrumentation request on their proposals).
Both new dichroics have much higher transmittance/reflectance and more
distinct transitions. More information is available on the
Common Path page.

Sept 18, 2016: The Red side CCD had been replaced with a new Hamamatsu
detector, yielding significantly better QE for wavelengths greater
than 5000 A. Readout noise is also significantly reduced. The new
detector is larger, so the wavelength coverage in a single image is
increased by about 20%. The Hamamatsu detector is a thick chip, so
fringing is not evident (especially compared to the previous Reticon
thinned CCD), except out towards 1 micron wavelengths.

The Kast has been in operation since early 1992. It was designed by
Dr. Joseph Miller (UCSC) and built in the Lick Observatory shops. The
instrument was made possible by a generous gift from William and
Marina Kast.